Predominant role of innate pro-inflammatory cytokines in vitiligo disease

Role of kinin receptors in skin pigmentation

Previous studies have shown that all kinin system is constitutively expressed in the normal and inflamed skin, with a potential role in both physiological and pathological processes. However, the understanding regarding the involvement of the kinin system in skin pigmentation and pigmentation disorders remains incomplete. In this context, the present study was designed to determine the role of kinins in the Monobenzone (MBZ)-induced vitiligo-like model. Our findings showed that MBZ induces higher local skin depigmentation in kinin receptors knockout mice (KOB1R, KOB2R and KOB1B2R) than in wild type (WT). Remarkably, lower levels of melanin content and reduced ROS generation were detected in KOB1R and KOB2R mice treated with MBZ. In addition, both KOB1R and KOB2R show increased dermal cell infiltrate in vitiligo-like skin, when compared to WT-MBZ. Additionally, lack of B1R was associated with greater skin accumulation of IL-4, IL-6, and IL-17 by MBZ, while KOB1B2R presented lower levels of TNF and IL-1. Of note, the absence of both kinin B1 and B2 receptors demonstrates a protective effect by preventing the increase in polymorphonuclear and mononuclear cell infiltrations, as well as inflammatory cytokine levels induced by MBZ. In addition, in vitro assays confirm that B1R and B2R agonists increase intracellular melanin synthesis, while bradykinin significantly enhanced extracellular melanin levels and proliferation of B16F10 cells. Our findings highlight that the lack of kinin receptors caused more severe depigmentation in the skin, as well as genetic deletion of both B1/B2 receptors seems to be linked with changes in levels of constitutive melanin levels, suggesting the involvement of kinin system in crucial skin pigmentation pathways.

Animal models unraveling the complexity of vitiligo pathogenesis

Vitiligo is a chronic skin condition marked by the gradual loss of pigmentation, leading to the emergence of white or depigmented patches on the skin. The exact cause of vitiligo remains not entirely understood, although it is thought to involve a blend of genetic, autoimmune, and environmental factors. While there is currently no definitive cure for vitiligo, diverse treatments exist that may assist in managing the condition and fostering repigmentation in specific instances. Animal models play a pivotal role in comprehending the intricate mechanisms that underlie vitiligo, providing valuable insights into the progression and onset of the disease, as well as potential therapeutic interventions. Although induced experimental models lack the nuanced characteristics observed in natural experimental models, relying solely on a single animal model might not fully capture the intricate pathogenesis of vitiligo. Different animal models simulate specific aspects of human vitiligo pathogenesis to varying degrees. This review extensively explores the array of animal models utilized in vitiligo research, shedding light on their respective advantages, disadvantages, and applications.

The Assessment of Infection Risk in Patients with Vitiligo Undergoing Dialysis for End-Stage Renal Disease: A Retrospective Cohort Study

Vitiligo is an autoimmune condition that causes patchy skin depigmentation. Although the mechanism by which vitiligo induces immunocompromise is unclear, other related autoimmune diseases are known to predispose those affected to infection. Individuals with vitiligo exhibit epidermal barrier disruption, which could potentially increase their susceptibility to systemic infections; patients with renal disease also show a predisposition to infection. Nevertheless, there is little research addressing the risk of infection in dialysis patients with vitiligo in comparison to those without it. A retrospective analysis was performed on patients with end-stage renal disease (ESRD) in the United States Renal Data System who started dialysis between 2004 and 2019 to determine if ESRD patients with vitiligo are at an increased risk of bacteremia, cellulitis, conjunctivitis, herpes zoster, or septicemia. Multivariable logistic regression modeling indicated that female sex, black compared to white race, Hispanic ethnicity, hepatitis C infection, and tobacco use were associated with an enhanced risk of vitiligo, whereas increasing age and catheter, versus arteriovenous fistula, and access type were associated with a decreased risk. After controlling for demographics and clinical covariates, vitiligo was found to be significantly associated with an increased risk of bacteremia, cellulitis, and herpes zoster but not with conjunctivitis and septicemia.

Improvements in immune/melanocyte biomarkers with JAK3/TEC family kinase inhibitor ritlecitinib in vitiligo

BACKGROUND

Vitiligo is an autoimmune depigmenting disorder with no effective and safe treatments. Its pathogenesis is not fully elucidated.

OBJECTIVE

This substudy of a randomized, double-blind, placebo-controlled phase 2b trial (NCT03715829) evaluated effects of ritlecitinib, an oral JAK3/TEC family kinase inhibitor, on skin and blood biomarkers in participants with nonsegmental vitiligo (NSV).

METHODS

Sixty-five adults with NSV participated in the substudy and received daily treatment for 24 weeks with placebo (n = 14) or ritlecitinib with or without a 4-week loading dose: 200 (loading dose)/50 mg (n = 13), 100/50 mg (n = 12), 50 mg (n = 11), 30 mg (n = 8), or 10 mg (n = 6). Skin (lesional and nonlesional) biopsy samples were obtained at baseline and at 4 and 24 weeks. Changes from baseline to weeks 4 and 24 in skin and blood molecular and cellular biomarkers were evaluated by RNA sequencing, quantitative real-time PCR, proteomic analysis, and flow cytometry.

RESULTS

Ritlecitinib-treated groups showed downregulation of immune biomarkers and upregulation of melanocyte-related markers at weeks 4 and 24 compared to baseline and/or placebo. Significant reductions were seen in CD3+/CD8+ T-cell infiltrates, with significant increases in melanocyte markers (tyrosinase; Melan-A) in NSV lesions in the 50 mg ritlecitinib groups (both P < .05). There was significant, dose-dependent downregulation in T-cell activation, NK, cytotoxic, and regulatory markers in lesional skin (IL-2, IL2-RA, IL-15, CCR7, CD5, CRTAM, NCR1, XCL1, KIR3DL1, FASLG, KLRD; P < .05). TH1 and TH2 markers were also downregulated in lesional skin and blood in a dose-dependent manner (P < .05). Changes in immune biomarkers correlated with clinical response.

CONCLUSIONS

Ritlecitinib significantly downregulated proinflammatory biomarkers and increased melanocyte products in skin and blood of participants with NSV, suggesting its potential in treatment. Ritlecitinib-mediated changes positively correlated with clinical response.

Restraint stress promotes monobenzone-induced depigmentation in mice via the activation of glucocorticoid receptor/macrophage migration inhibitory factor signaling pathway

Psychological stress triggers onset and development of vitiligo in humans. However, the mechanism of psychological stress on vitiligo remains unclear. The study aims to investigate whether psychological stress promotes vitiligo and explore the underlying mechanism. A depigmentation mouse model induced by applying a skin-bleaching reagent monobenzone to dorsal skin and an in vitro HaCaT keratinocyte death model induced by monobenzone were employed to explore the effect of restraint stress, which mimics psychological stress, on depigmentation. The results indicated that restraint stress promoted vitiligo-related depigmentation, vacuolisation, spongiosis, CD8+ T lymphocyte infiltration, and loss of melanocytes in the skin. Restraint stress activated cutaneous NLR family containing pyrin domain protein 3 (NLRP3) inflammasome. In addition, restraint stress aggravated anxiety-like behaviors and increased levels of macrophage migration inhibitory factor (MIF) and corticosterone in the circulation, accompanied with decreasing the expression of cutaneous 8-oxoguanine DNA glycosylase (OGG1) in depigmentation mice. In vitro experiments demonstrated that activation of glucocorticoid receptor (GR) by cortisol upregulated NLRP3 expression dependent on MIF, and directly decreased the transcription of OGG1. Blockade of MIF reversed the NLRP3 signal in restraint stress-induced depigmentation mice. In conclusion, restraint stress promotes vitiligo-related depigmentation in mice via the activation of GR/MIF signaling pathway. The findings provide a theoretical basis for prevention and treatments of vitiligo with therapies of targeting GR, MIF, and OGG1.

Evaluation of serum and tissue levels of cold-inducible RNA-binding protein in non-segmental Vitiligo

Damage-associated molecular patterns (DAMPs) play a role in the pathogenesis of vitiligo. It has been established that the cold-inducible RNA-binding protein (CIRP), a member of the family of cold-shock proteins that respond to stress, is a DAMP molecule that promotes inflammation. The objective was to evaluate the serum and tissue CIRP expression in non-segmental vitiligo (NSV) patients. A sample of 40 participants, 20 NSV patients and 20 control groups of age- and sex-matched healthy individuals were included in this case-control study where the enzyme-linked immunosorbent assay was used in detecting the serum and tissue CIRP levels in participants. The serum and tissue CIRP levels significantly increased in NSV patients compared with the healthy controls, (165.35 ± 24.42, 226.29 ± 24.00 versus 59.81 ± 12.10, 105.86 ± 11.27 pg/ml, respectively) (P < 0.01). Serum and tissue CIRP are significantly correlated with each other (r = 0.641, P = 0.002). Except for a statistically significant positive correlation between CIRP tissue level and VASI (r = 0.539, P = 0.014), the CIRP Serum and tissue did not show any statistically significant correlations with different clinical parameters in patients. ROC curve shows that the cut-off point for serum and tissue CIRP level to differentiate between patients and controls was 86.5, 124.3 pg/ml, respectively, with 100.0% sensitivity, 100.0% specificity and 1.000 AUC for each of them. It is concluded that CIRP may have a crucial role in the pathogenesis of NSV and could be used as a marker for vitiligo and its extent with the need for further large-scale study.

Association of rs4711998 of IL-17A, rs2275913 of IL-17A and rs763780 IL-17F gene polymorphisms with non-segmental vitiligo in a Mexican population

Vitiligo is the most common depigmenting disease characterized by achromic macules due to selective loss of melanocytes. The pathogenesis remains poorly elucidated, and multiple hypotheses exist regarding its pathogenesis. Evidence suggests that stress on melanocytes can result in activation of the immune system, and involvement of both activated cluster of differentiation (CD8+) cytotoxic and CD4+ T cells in the dysfunction, depigmentation, and apoptosis of melanocytes. Recent studies show that the interleukin 17 (IL-17) axis plays a central role in the pathogenesis of the disease. IL-17 is an important regulatory effector cytokine in this pathway. The aim of this study was to evaluate the association of IL-17A rs4711998 (-832A/G), IL-17A rs2275913 (-197G/A), and IL-17F rs763780 (7488A/G) with vitiligo in a Northeastern Mexican population. This was a case-control study and included 116 patients with vitiligo and 116 control subjects. Genotype characterization of IL-17A rs4711998 (-832A/G), IL-17A rs2275913 (-197G/A), and IL-17F rs763780 (7488A/G) was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. A p ≤ 0.05 was considered significant. It was observed that the combination of the genotypes GG/GA for IL-17F rs763780 (7488A/G) was associated with an increased risk for the development of vitiligo (OR 2.0943, 95% Cl 1.2375-3.5445, p = 0.0056). Regarding IL-17A rs4711998 (-832A/G) and IL-17A rs2275913 (-197G/A) genotyping, no association with vitiligo development was found. In conclusion, the SNP rs763780 in the IL-17F gene appears to be a risk factor for vitiligo development in this Mexican population and it may be useful in future studies, especially for the development of new therapies.

Based on network pharmacology and bioinformatics to analyze the mechanism of action of Astragalus membranaceus in the treatment of vitiligo and COVID-19

Coronavirus disease 2019 (COVID-19) is spreading rapidly around the world. However, the treatment of vitiligo combined with COVID-19 has not been reported. Astragalus membranaceus (AM) has a therapeutic effect on patients with vitiligo and COVID-19. This study aims to discover its possible therapeutic mechanisms and provide potential drug targets. Using the Chinese Medicine System Pharmacological Database (TCMSP), GEO database and Genecards websites and other databases, AM target, vitiligo disease target, and COVID-19 related gene set were established. Then find the crossover genes by taking the intersection. Then use GO, KEGG enrichment analysis, and PPI network to discover its underlying mechanism. Finally, by importing drugs, active ingredients, crossover genes, and enriched signal pathways into Cytoscape software, a "drug-active ingredient-target signal pathway-" network is constructed. TCMSP screened and obtained 33 active ingredients including baicalein (MOL002714), NEOBAICALEIN (MOL002934), Skullcapflavone II (MOL002927), and wogonin (MOL000173), which acted on 448 potential targets. 1166 differentially expressed genes for vitiligo were screened by GEO. CIVID-19 related genes were screened by Genecards. Then by taking the intersection, a total of 10 crossover genes (PTGS2, CDK1, STAT1, BCL2L1, SCARB1, HIF1A, NAE1, PLA2G4A, HSP90AA1, and HSP90B1) were obtained. KEGG analysis found that it was mainly enriched in signaling pathways such as IL-17 signaling pathway, Th17 cell differentiation, Necroptosis, NOD-like receptor signaling pathway. Five core targets (PTGS2, STAT1, BCL2L1, HIF1A, and HSP90AA1) were obtained by analyzing the PPI network. The network of "active ingredients-crossover genes" was constructed by Cytoscape, and the 5 main active ingredients acting on the 5 core crossover genes acacetin, wogonin, baicalein, bis2S)-2-ethylhexyl) benzene-1,2-dicarboxylate and 5,2'-Dihydroxy-6,7,8-trimethoxyflavone. The core crossover genes obtained by PPI and the core crossover genes obtained by the "active ingredient-crossover gene" network are intersected to obtain the three most important core genes (PTGS2, STAT1, HSP90AA1). AM may act on PTGS2, STAT1, HSP90AA1, etc. through active components such as acacetin, wogonin, baicalein, bis2S)-2-ethylhexyl) benzene-1,2-dicarboxylate and 5,2'-Dihydroxy-6,7,8-trimethoxyflavone to activate IL-17 signaling pathway, Th17 cell differentiation, Necroptosis, NOD-like receptor signaling pathway, Kaposi sarcoma-associated herpesvirus infection, and VEGF signaling pathway and other signaling pathways to achieve the effect of treating vitiligo and COVID-19.

Beyond skin white spots: Vitiligo and associated comorbidities

Vitiligo is a common depigmentation disorder of an unknown origin characterized by the selective loss of melanocytes, resulting in typical white macules and patches. However, vitiligo is now recognized as more than just a skin disease, what a dermatologist observes as a white spot of skin is just the "tip of the iceberg" of the condition. We attempt to clarify the classification of comorbidities associated with vitiligo from various reviews and reports, and describe their possible pathogenesis. In conclusion, the literature provides evidence of an association between vitiligo and ocular and auditory abnormalities, autoimmune disorders, other dermatological diseases, metabolic syndrome and related disorders, and psychological diseases. These associations highlight the importance of a multidisciplinary approach in managing vitiligo patients.

Circulatory levels of alarmins in patients with non-segmental vitiligo: Potential biomarkers for disease diagnosis and activity/severity assessment

Background

Non-segmental vitiligo (NSV) is an autoimmune skin disorder that is difficult to determine disease activity/severity and thus to treat. Alarmins have emerged as promising biomarkers in various diseases, so further confirmation of their potential roles in NSV would be of considerable value. With the present work, we aimed to determine the serum levels of alarmins in patients with NSV, correlate these alarmins with disease activity and severity, and analyze the predictive value of the combination of these markers.

Methods

104 NSV patients and 56 healthy controls were enrolled at the Xijing Hospital of Fourth Military Medical University between September 1, 2018, and June 30, 2019. The serum levels of alarmins (including IL-33, IL-1α, S100A9, S100A12, S100B, and HMGB1) were measured with enzyme-linked immunosorbent assays. The predictive performance of these biomarkers was evaluated with the area under the receiver operating characteristic curve (AUC), sensitivity, specificity, and other representative statistics.

Results

A total of 104 patients with NSV (mean [SD] age, 34.2 [13.0] years; 62 [59.6%] male) and 56 healthy controls (mean [SD] age, 34.8 [13.5] years; 34 [60.7%] male) were enrolled. For vitiligo diagnosis, S100B had the highest sensitivity (92.31%), whereas HMGB1 had the highest specificity (85.71%); the combination of IL-1α, S100B, S100A9, and HMGB1 increased the AUC value to 0.925, with a sensitivity of 87.50% and a specificity of 85.71%. Multivariate logistic regression analysis showed S100B (OR, 1.019; 95% CI, 1.002-1.038; P =0.03), S100A9 (OR, 1.002; 95% CI, 1.001-1.003; P<0.001), and HMGB1 (OR, 1.915; 95% CI, 1.186-3.091; P =0.008) were significantly associated with vitiligo activity. S100A9 had the highest accuracy in discriminating patients at the active stage from the stable stage, with an AUC value of 0.827. The combination of these alarmins had an AUC value of 0.860 to assess disease activity, with a sensitivity of 90.00% and a specificity of 72.97%. Furthermore, S100B (r=0.61, P <0.001), S100A9 (r=0.33, P <0.001), and HMGB1 (r = 0.51, P <0.001) levels were positively correlated with the affected body surface area (BSA) in NSV patients.

Conclusions

Serum S100B, S100A9, and HMGB1 might be biomarkers for diagnosing and assessing the activity/severity of NSV, either used alone or in combination.

The role of cytokines and vitamin D in vitiligo pathogenesis

Vitiligo is a pigment-related disease with a global prevalence of 0.2% to 1.8% associated with considerable burden on quality of life. The treatment is still a challenge because of relapses and/or incomplete re-pigmentation. Although the exact cause is still unclear, its pathogenesis seems to be justifiable with the autoimmune theory, supported by the results of clinical research. In this narrative review, we aimed to summarize the evidence related to cytokines and vitiligo development. This review is consisted of English articles published in PubMed and Google Scholar concerning levels of inflammatory mediators, especially interleukins, in vitiligo patients over the last 20 years. References of relevant articles were also considered for review. Crucial role of dysregulated levels of interleukins and their synergistic function to each other, in the onset or progression of the disease is evident. The theory of autoimmune vitiligo is reinforced by the results of the studies in the literature, due to the association of pathogenesis with increased secretion of pro-inflammatory mediators and reduction of anti-inflammatory mediators. Decreased vitamin D levels may have a considerable role in vitiligo development by affecting Th1- and Th17-related immune responses. Cytokines play an important role in the pathogenesis or progression of the disease. Moreover, we believe that decreased vitamin D level has a considerable role in vitiligo development by affecting Th1- and Th17-related immune responses.

Current Concepts of Vitiligo Immunopathogenesis

Vitiligo is an acquired immune-mediated disorder of pigmentation clinically characterized by well-defined depigmented or chalk-white macules and patches on the skin. The prevalence of vitiligo varies by geographical area, affecting 0.5% to 2% of the population. The disease imposes a significant psychological burden due to its major impact on patients’ social and emotional aspects of life. Given its autoimmune background, vitiligo is frequently associated with other autoimmune diseases or immune-mediated diseases. Vitiligo is a multifaceted disorder that involves both genetic predisposition and environmental triggers. In recent years, major predisposing genetic loci for the development of vitiligo have been discovered. The current findings emphasize the critical role of immune cells and their mediators in the immunopathogenesis of vitiligo. Oxidative-stress-mediated activation of innate immunity cells such as dendritic cells, natural killer, and ILC-1 cells is thought to be a key event in the early onset of vitiligo. Innate immunity cells serve as a bridge to adaptive immunity cells including T helper 1 cells, cytotoxic T cells and resident memory T cells. IFN-γ is the primary cytokine mediator that activates the JAK/STAT pathway, causing keratinocytes to produce the key chemokines CXCL9 and CXCL10. Complex interactions between immune and non-immune cells finally result in apoptosis of melanocytes. This paper summarizes current knowledge on the etiological and genetic factors that contribute to vitiligo, with a focus on immunopathogenesis and the key cellular and cytokine players in the disease’s inflammatory pathways.

Update on the pathogenesis of vitiligo

Vitiligo is a complex disease whose pathogenesis results from the interaction of genetic components, metabolic factors linked to cellular oxidative stress, melanocyte adhesion to the epithelium, and immunity (innate and adaptive), which culminate in aggression against melanocytes. In vitiligo, melanocytes are more sensitive to oxidative damage, leading to the increased expression of proinflammatory proteins such as HSP70. The lower expression of epithelial adhesion molecules, such as DDR1 and E-cadherin, facilitates damage to melanocytes and exposure of antigens that favor autoimmunity. Activation of the type 1-IFN pathway perpetuates the direct action of CD8+ cells against melanocytes, facilitated by regulatory T-cell dysfunction. The identification of several genes involved in these processes sets the stage for disease development and maintenance. However, the relationship of vitiligo with environmental factors, psychological stress, comorbidities, and the elements that define individual susceptibility to the disease are a challenge to the integration of theories related to its pathogenesis.

Mitochondrial RNA processing defect caused by a SUPV3L1 mutation in two siblings with a novel neurodegenerative syndrome

SUPV3L1 encodes a helicase that is mainly localized in the mitochondria. It has been shown in vitro to possess both double-stranded RNA and DNA unwinding activity that is ATP-dependent. Here we report the first two patients for this gene who presented with a homozygous preliminary stop codon resulting in a C-terminal truncation of the SUPV3L1 protein. They presented with a characteristic phenotype of neurodegenerative nature with progressive spastic paraparesis, growth restriction, hypopigmentation, and predisposition to autoimmune disease. Ophthalmological examination showed severe photophobia with corneal erosions, optic atrophy, and pigmentary retinopathy, while neuroimaging showed atrophy of the optic chiasm and the pons with calcification of putamina, with intermittent and mild elevation of lactate. We show that the amino acids that are eliminated by the preliminary stop codon are highly conserved and are predicted to form an amphipathic helix. To investigate if the mutation causes mitochondrial dysfunction, we examined fibroblasts of the proband. We observed very low expression of the truncated protein, a reduction in the mature ND6 mRNA species as well as the accumulation of double-stranded RNA. Lentiviral complementation with the full-length SUPV3L1 cDNA partly restored the observed RNA phenotypes, supporting that the SUPV3L1 mutation in these patients is pathogenic and the cause of the disease.

Patho-immunological mechanisms of vitiligo: the role of the innate and adaptive immunities and environmental stress factors

Epidermal melanocyte loss in vitiligo, triggered by stresses ranging from trauma to emotional stress, chemical exposure or metabolite imbalance, to the unknown, can stimulate oxidative stress in pigment cells, which secrete damage-associated molecular patterns that then initiate innate immune responses. Antigen presentation to melanocytes leads to stimulation of autoreactive T-cell responses, with further targeting of pigment cells. Studies show a pathogenic basis for cellular stress, innate immune responses and adaptive immunity in vitiligo. Improved understanding of the aetiological mechanisms in vitiligo has already resulted in successful use of the Jak inhibitors in vitiligo. In this review, we outline the current understanding of the pathological mechanisms in vitiligo and locate loci to which therapeutic attack might be directed.

New insights into segmental vitiligo: A clinical and immunological comparison with nonsegmental vitiligo

The overlaps between segmental vitiligo (SV) and nonsegmental vitiligo (NSV) suggest the underlying features of SV, which may be helpful for treating SV. In this study, 379 vitiligo patients were recruited and divided into SV (33.2%), mild-to-moderate NSV (M-NSV, affected body affected area [BSA] ≤10%, 34.0%), and severe NSV (S-NSV, affected BSA >10%, 32.7%) groups. Demographics and clinical data were collected through in-person interviews. The disease activity, progression, and prognosis were assessed through 6 months' follow-up. Serum cytokines profile and tissue-infiltrating immune cells were measured by ELISA assay and immunofluorescence, respectively. The SV exhibited lower rates of autoimmune comorbidities and recurrence than the S-NSV, but performed similar to the M-NSV. Moreover, the disease activity, progression, serum cytokines profile, and tissue-infiltrating Th/c1 cells in the active SV and M-NSV were comparable, but differed significantly from those of the active S-NSV. The clinical and immunological similarities between SV and M-NSV presented a deeper autoimmune understanding of SV. Additionally, a classification of active vitiligo according to disease extent may be more clinically meaningful than subtypes for guiding immunomodulatory treatment.

Interleukin 38 serum level is increased in patients with vitiligo, correlated with disease severity, and associated with signs of disease activity

BACKGROUND

Vitiligo is an acquired cutaneous depigmenting disease caused by a T helper (Th) 1-cytotoxic T cells driven autoimmune attack against melanocytes, in which Th17 is also involved. Interleukin (IL)-38 belongs to the IL-1 family of cytokines and suppresses Th1 and Th17 activation. IL-38 protein and mRNA levels have been found to be elevated in various autoimmune disorders and correlated with disease severity and activity, including psoriasis, systemic sclerosis, rheumatoid arthritis, and atopic dermatitis. No previous studies have been performed to investigate the expression of IL-38 in patients with vitiligo.

AIM

To evaluate IL-38 serum level in patients with vitiligo compared to healthy controls (Hcs) and examine the association between IL-38 level and severity and activity of vitiligo.

PATIENTS AND METHODS

The study comprised 21 patients with vitiligo and 21 Hcs. Vitiligo severity and activity were evaluated via Vitiligo Extent Score (VES) and Vitiligo Disease Activity (VIDA) Score, respectively. IL-38 serum level was evaluated by enzyme-linked immunosorbent assay.

RESULTS

Vitiligo patients had significantly higher serum level of IL-38 than Hcs (p < 0.001). This level was significantly higher among patients with signs of vitiligo activity (p = 0.048), correlated positively with VES (p < 0.001), and correlated negatively with the age of patients (p = 0.001) and the age of disease onset (p = 0.022).

CONCLUSION

IL-38 serum level was higher in patients with vitiligo than in Hcs and was related to vitiligo severity and signs of activity.

Targeted Therapies in Autoimmune Skin Diseases

Unlike the established anti-inflammatory drugs with a broad range, new-targeted therapeutic approaches have emerged in the management of autoimmune skin diseases to increase efficacy and decrease adverse reactions on the basis of an improved molecular understanding of pathogenesis. Most inflammatory dermatoses are driven by misled immune responses physiologically directed at exogenous pathogens, that is, type 1 immunity against viral pathogens, type 2 immunity against parasites, and type 3 immunity against fungi and bacteria. Pathogenic hallmarks of these major immune reaction patterns are characterized within this article, and a comprehensive overview of current clinical trials evaluating targeted therapeutics for respective dermatoses is outlined.

Transcriptome and Differential Methylation Integration Analysis Identified Important Differential Methylation Annotation Genes and Functional Epigenetic Modules Related to Vitiligo

Vitiligo is an pigmentation disorder caused by a variety of pathogenic factors; its main pathophysiological conditions include oxidative stress, immune activation, and genetic background. Additionally, DNA methylation is often associated with the pathogenesis of vitiligo; however, the underlying mechanism remains unknown. In the present study, we used the Human Methylation 850K BeadChip platform to detect DNA methylation changes in the vitiligo melanocytes. We then integrated the results with the transcriptome data of vitiligo melanocytes and lesions to analyse the correlation between differentially methylated levels and differentially expressed genes. The results showed that there was a significant negative correlation between methylation levels and differentially expressed genes. Subsequently, we enriched GO and KEGG based on methylated differentially expressed genes (MDEGs) using R package ClusterProfiler, and the results were closely related to the pathogenesis of vitiligo. In addition, we also constructed a PPI network of MDEGs and excavated three important functional epigenetic modules, involving a total of 12 (BCL2L1, CDK1, ECT2, HELLS, HSP90AA1, KIF23, MC1R, MLANA, PBK, PTGS2, SOX10, and TYRP1) genes. These genes affect melanocyte melanogenesis, cellular oxidative stress and other important biological processes. Our comprehensive analysis results support the significant contribution of the status of DNA methylation modification to vitiligo, which will help us to better understand the molecular mechanism of vitiligo and explore new therapeutic strategies.

The Role of the NKG2D in Vitiligo

Vitiligo is an acquired multifactorial disease that affects melanocytes and results in skin depigmentation. In this review, we examine the role of cells stress and self-reactive T cells responses. Given the canonical and non-canonical functions of NKG2D, such as authenticating stressed target and enhance TCR signaling, we examine how melanocyte stress leads to the expression of ligands that are recognized by the activating receptor NKG2D, and how its signaling results in the turning of T cells against self (melanocyte suicide by proxy). We also discuss how this initiation phase is followed by T cell perpetuation, as NKG2D signaling results in self-sustained long-lasting T cells, with improved cytolytic properties.

Immune-modulatory effects of lenalidomide inhibited the progression of lesions in a vitiligo mouse model

Vitiligo, an autoimmune disorder, is associated with altered cytokine levels and T lymphocytes. Lenalidomide modulates immune system components by altering cytokine production and regulating T-cell stimulation. In this study, effect of lenalidomide was checked on the development of vitiligo lesions, level of various cytokines, and T lymphocytes in the mouse model. The vitiligo mouse model was developed by immunizing C57BL/6 mouse with anti-mouse tyrosine-related protein 2. Lenalidomide was orally given to mice daily, and the effect was observed on the development of vitiligo lesions. The level of T lymphocytes in blood was checked by flow cytometry. Serum cytokine levels were checked by enzyme-linked immunosorbent assay. Vitiligo lesions were found significantly smaller in lenalidomide-treated mice models. It significantly decreased the serum levels of IFN-γ, TNF-α, IL-1β, and IL-6 but elevated the levels of IL-4 and IL-10. It non-significantly elevated CD4⁺ /CD8⁺ T-cell ratio. Lenalidomide had an inhibitory effect on the development of vitiligo lesions in mice models by suppressing the serum level of pro-inflammatory cytokines and increasing anti-inflammatory cytokine levels. It modulated the immune response in vitiligo mice models toward an anti-inflammatory profile suggesting its use in the management of vitiligo.

Case Series: Gene Expression Analysis in Canine Vogt-Koyanagi-Harada/Uveodermatologic Syndrome and Vitiligo Reveals Conserved Immunopathogenesis Pathways Between Dog and Human Autoimmune Pigmentary Disorders

Vogt-Koyanagi-Harada syndrome (VKH) and vitiligo are autoimmune diseases that target melanocytes. VKH affects several organs such as the skin, hair follicle, eyes, ears, and meninges, whereas vitiligo is often limited to the skin and mucosa. Many studies have identified immune genes, pathways and cells that drive the pathogeneses of VKH and vitiligo, including interleukins, chemokines, cytotoxic T-cells, and other leukocytes. Here, we present case studies of 2 canines with VKH and 1 with vitiligo, which occurred spontaneously in client-owned companion dogs. We performed comparative transcriptomics and immunohistochemistry studies on lesional skin biopsies from these cases in order to determine if the immunopathogenesis of autoimmune responses against melanocytes are conserved. In dogs, we found enrichment of T cell gene signatures, with upregulation of IFNG, TNF, PRF1, IL15, CTSW, CXCL10, and CCL5 in both VKH and vitiligo in dogs compared to healthy controls. Similar findings were reported in humans, suggesting that these genes play a role in the pathogenesis of spontaneous VKH and vitiligo. T cell-associated genes, including FOXP3 and TBX21, were enriched, while IGFBP5, FOXO1, and PECAM1 were decreased compared to healthy controls. Further, we identified TGFB3, SFRP2, and CXCL7 as additional potential drivers of autoimmune pigmentary disorders. Future studies exploring the immunopathogenesis of spontaneous autoimmunity will expand our understanding of these disorders, and will be useful in developing targeted therapies, repurposing drugs for veterinary and human medicine, and predicting disease prognosis and treatment response.

JAK1 Inhibition Blocks Lethal Immune Hypersensitivity in a Mouse Model of Down Syndrome

Individuals with Down syndrome (DS; trisomy 21) display hyperactivation of interferon (IFN) signaling and chronic inflammation, which could potentially be explained by the extra copy of four IFN receptor (IFNR) genes encoded on chromosome 21. However, the clinical effects of IFN hyperactivity in DS remain undefined. Here, we report that a commonly used mouse model of DS overexpresses IFNR genes and shows hypersensitivity to IFN ligands in diverse immune cell types. When treated repeatedly with a TLR3 agonist to induce chronic inflammation, these animals overexpress key IFN-stimulated genes, induce cytokine production, exhibit liver pathology, and undergo rapid weight loss. Importantly, the lethal immune hypersensitivity and cytokine production and the ensuing pathology are ameliorated by JAK1 inhibition. These results indicate that individuals with DS may experience harmful hyperinflammation upon IFN-inducing immune stimuli, as observed during severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, pointing to JAK1 inhibition as a strategy to restore immune homeostasis in DS.

Association between vitiligo and subsequent risk of dementia: A population-based cohort study

Increasing evidence suggests a positive association between autoimmune disorders and the subsequent risk of dementia, supporting the idea that neuroinflammation is a major contributor to dementia. However, whether or not adults with vitiligo have an increased risk of dementia remains unclear. We aimed to investigate the association between vitiligo and the subsequent risk of dementia. A total of 1320 patients with vitiligo and 5280 matched controls were identified from the Taiwan National Health Insurance Research Database between 1998 and 2011. Dementia was diagnosed by board-certificated psychiatrists or neurologists in the follow-up period. Cox proportional hazards models were used to estimate the adjusted hazard ratios (aHR) after controlling for age, sex, income-related monthly premium, residence and comorbidities associated with dementia. The incidence rate of dementia (per 100 000 person-years) was 502.8 among patients with vitiligo and 101.9 among the controls. Patients with vitiligo were more likely to develop any type of dementia (aHR, 5.30; 95% confidence interval [CI], 3.30-8.51), Alzheimer's disease (aHR, 12.22; 95% CI, 3.71-40.28) and vascular dementia (aHR, 3.99; 95% CI, 1.31-12.15) compared with the controls. In conclusion, middle-aged and old patients with vitiligo are more likely to develop dementia compared with those without vitiligo. This novel finding reminds physicians to be more careful about signs of dementia when managing patients with vitiligo and provides the basis for further investigations that clarify the underlying mechanisms.

Support for increased cardiovascular risk in non-segmental vitiligo among Egyptians: A hospital-based, case-control study

BACKGROUND

Data have been accumulating in the past few years that identify vitiligo as a disorder with systemic implications.

RESULTS AND METHODS

In this hospital-based, cross-sectional, case-control study, 50 patients with non-segmental vitiligo and 50 age- and sex-matched controls underwent analysis of serum lipid profile, oxidative stress biomarkers and carotid duplex. Hydrogen peroxide (H₂ O₂ ) and malondialdehyde (MDA) were significantly higher in patients than controls (p-value < .001, <.001, respectively); on the other hand, total antioxidant capacity (TAC) was significantly lower in patients than controls (p-value = .001). A significantly higher percentage of patients had hypercholesterolemia and borderline high, high or very high levels of LDL-C, compared to controls (p-value = .001 and .001, respectively). Atherosclerotic plaques and increased common carotid intima media thickness were significantly detected in patients versus controls.

DISCUSSION

Results of the present study suggest that a subset of patients with vitiligo are at a higher risk of developing dyslipidemia and atherosclerosis, which might increase their future risk for the development of cardiovascular disease. Confirmation of these findings would subsequently influence investigative and the treatment strategies in the management plan of vitiligo patients in the near future.

SIGNIFICANCE

Vitiligo patients might be at a higher risk of developing dyslipidemia and atherosclerosis, which might increase their risk for the development of cardiovascular disease necessitating prophylactic measures to improve prognosis. Our results might influence the investigative and treatment strategies in the management plan of vitiligo patients in the near future.

Immune modulatory effects of lenalidomide on the cultured peripheral blood mononuclear cells from vitiligo patients

Vitiligo is a depigmentary disease in which epidermal melanocytes are lost. It is considered to be an autoimmune disease. Lenalidomide, an immunomodulatory drug is being employed in the treatment of various autoimmune and inflammatory disorders. In the present manuscript, the effect of lenalidomide on T cells and major cytokines in the cultured peripheral blood mononuclear cells (PBMCs) derived from vitiligo patients was checked. Eight patients with a clinical diagnosis of active vitiligo volunteered for the study. Blood was collected from them and PBMCs were isolated, cultured, and treated with lenalidomide. After 72 hours, PBMCs were harvested and checked for CD8⁺ and CD4⁺ T cells by flow cytometry. Further supernatant was collected and the levels of cytokines namely tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ), interleukin-10 (IL-10), and interleukin-4 (IL-4) were checked using ELISA kits. Lenalidomide nonsignificantly decreased the level of CD8⁺ T cells but increased CD4⁺ T cells leading to increased CD4⁺ /CD8⁺ T cell ratio. It declined the level of pro-inflammatory cytokines, that is, TNF-α and IFN-γ whereas elevated anti-inflammatory cytokines, that is, IL-10 and IL-4, thus ultimately decreasing the ratio of pro-inflammatory to anti-inflammatory cytokines. Lenalidomide suppressed the proliferation of T lymphocytes and modulated the cytokines secretion toward an anti-inflammatory profile.

Tranilast Directly Targets NLRP3 to Protect Melanocytes From Keratinocyte-Derived IL-1β Under Oxidative Stress

The activation of NLRP3 inflammasome-IL-1β pathway in keratinocytes contributes to the melanocyte death via autoimmunity-dependent manner in vitiligo. As a safe small-compound drug employed frequently in clinic, tranilast (TR) is newly reported to block the activation of NLRP3 inflammasome in macrophage. Nevertheless, whether keratinocyte-derived IL-1β damages melanocytes in an autoimmunity-independent way and whether TR could ameliorate the melanocyte damage via inhibiting the NLRP3-IL-1β pathway in keratinocyte still are not clear. In the present study, we initially found that TR could impede the secretion of IL-1β from keratinocytes by interfering the NLRP3 oligomerization. More importantly, we illustrated that TR could decrease the melanocyte apoptosis, improve the melanogenesis, and have the capacity to optimize the melanosome translocation by abolishing the keratinocyte-derived IL-1β. Additionally, TR could mitigate the secretion of inflammatory cytokines such as IL-6, IL-8, TNF-α, and IL-18 in keratinocytes under oxidative stress. In short, our data indicate that IL-1β plays detrimental roles in the melanocyte survival, melanogenesis, melanosome translocation and the secretion of inflammatory cytokines, and TR could be a promising therapeutic strategy in vitiligo by attenuating the keratinocyte-derived IL-1β under oxidative stress.

Decreased levels of interleukin 27 in the serum of vitiligo patients

BACKGROUND

Vitiligo is a common skin disorder in which melanocytes are destroyed by auto-reactive immune responses. The loss of melanocytes results in the appearance of depigmented areas in different parts of the body. Cytokines have remarkable roles in the pathogenesis of vitiligo, such as IL-1, IL-6, and TNF-α; interleukin 27 (IL-27) is a new member of the IL-6/IL-12 family, mainly released by activated antigen-presenting cells. IL-27 has been suggested to function as a pro-inflammatory as well as an anti-inflammatory cytokine. Altered concentrations of IL-27 have been shown in various auto-immune diseases such as multiple sclerosis, rheumatoid arthritis, and psoriasis. No studies have been conducted to determine the expression of this cytokine in vitiligo patients.

OBJECTIVE

The objective of this study was to determine the serum concentration of IL-27 in vitiligo patients and compare it with normal individuals.

METHODS

The serum concentration of IL-27 in 79 vitiligo patients was evaluated in comparison to 45 healthy controls using ELISA assay.

RESULTS

Results showed decreased concentration of IL-27 in vitiligo patients as compared with healthy subjects (p=0.026). Furthermore, no correlation between IL-27 concentrations and disease parameters such as vitiligo severity and the extension of the depigmented area was observed.

STUDY LIMITATION

A larger sample size would be more recommended for this study.

CONCLUSION

The reduction in the serum levels of IL-27 in vitiligo patients compared to normal subjects suggested the possible anti-inflammatory role of this cytokine in vitiligo. Thus, IL-27 may be considered as a new target for the manipulation of the immune system in vitiligo patients.